import java.util.Scanner;


public class Task03 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		float x = sc.nextFloat();
		float mult = x;
		
		do {
			x = sc.nextFloat();
			mult *= x;
		} while (x != 1);
		
		System.out.println(mult);
		sc.close();
	}

}
